Many reports have been made on the microcapsules and their production methods. Among them, complex coacervation method, simple coacervation method, interfacial polymerization method and in situ polymerization method are known as the methods for physicochemically and chemically producing microcapsules. These methods are practically used in many fields of art owing to the advantages such as no necessity of using specific devices, capability of producing the capsules of the desired particle sizes in the range from submicron level to the order of several millimeters and capability of controlling the properties and denseness of the capsule wall.
However, the coacervation methods, in which gelatin-gum arabic type natural polymers are most generally used as capsule wall material, have the defects that the capsule made of said polymeric substances are poor in water resistance and costly, that it is hard to obtain a capsule solution of high concentration, and that the encapsulization process is complicate. On the other hand, the chemical production methods such as interfacial polymerization method and in situ polymerization method have the problems that the raw material of capsule wall reacts with the core material to be encapsulated due to high reactivity of the raw material, and that the core material is exposed to a strong acid or alkali, so that these methods are not necessarily satisfactory ones.